Brake control device



April 14, 1942. w LOGAN, JR 2,279,433

BRAKE CONTROL DEVICE Filed March 23, 19:59 :5 Sheets-Sheet 1 I INVENTORJOHN W. LOGAN,JR.

ATTORNEY,

April 9 J. w. LOGAN, JR

BRAKE CONTROL DEVICE Filed March 23, 1959 3 Sheets Sh eet 2 Ill IINVENTOR JOHN W. LOGAN,JR.

ATTORNEY Patented Apr. 14, 1942 UNITED STATES, PATENT OFFICE BRAKECONTROL DEVICE John W. Logan, Jr., Forest Hills, Pa., assignor to TheWestinghouse Air" Brake Company, Wilmerding, Pa., a corporation ofPennsylvania Application March 23, 1939, Serial No. 263,591

9 Claims. ,(Cl. 30321) This invention relates to brake control devicesand has particular relation to control apparatus for vehicle wheelbrakes including means responsive to the torque exerted on the wheelbrakes during application thereof for regulating and controlling thedegree of the brake application.

In my prior Patent 2,014,903, there is disclosed and claimed a vehiclewheel brake apparatus including a movable member subject to the torqueexerted on the vehicle wheel brakes and a flexible leaf spring whichyieldingly permits movement of the torque member only when the torque onthe member exceeds a certain uniform value. Movement of the torquemember is utilized to so limit the degree of the brake application as toprevent the locking of the vehicle wheels and the consequent slidingthereof under normal conditions of adhesion between the vehicle wheelsand the road surface or rails.

In my present invention, I propose to provide a torque responsivemechanism wherein the torque exerted on the wheel brake devices isopposed by a force which varies in correspondence with the desireddegree of application of the brakes. By thus varying the force resistingthe torque force on the wheel brake devices according to the degree ofthe desired brake application, it is possible to regulate the degree ofbrake application oneach individual wheel and axle unit to any one of aplurality-of different degrees dependent upon the degree of brakeapplication selected, as distinguished from only one given degree as inmy prior Patent 2,014,903. Also each wheel and axle unit isautomatically braked so as to contribute its proper share of the totalbraking effort.

It is accordingly an object of my invention to provide brake controlapparatus including means responsive to the torque exerted on wheelbrake devices for regulating the degree of the brake application on anindividual wheel and axle unit to any one of a plurality of differentvalues selected by the operator.

The above object, and other objects of my invention which will be madeapparent hereinafter, are obtained by means of several illustrativeembodiments of my invention subsequently to be described and shown inthe accompanying drawings wherein Fig. 1 is a plan View of a tractionvehicle wheel truck, showing the manner ofapplication of my inventionthereto,

Fig. 2 is a diagrammatic and partly sectional view showing oneembodiment of my invention, Fig. 3 is a sectional View, taken on theline 33 of Fig. 2, showing further details of construction,

Fig. 4 is an enlarged sectional view showing the construction of theslide valve mechanism indicated in outline form in Fig. 2,

Fig. 5 is a diagrammatic and partly sectional view showing a secondembodiment of my invention, and

Figs. 6, 7, 8 and 9 are enlarged views showing details of constructionof the embodiment shown in Fig. 5. r

Description of equipment Referring to Fig. l, a typical four wheel truckisshown having two axles l0 and H to which the vehicle wheels l2 arefixed and two traction motors l3 and [4 arranged longitudinally of thewheel truck and adapted to-drive the axles l0 and l l respectively. Aswill be apparent, the shaft of each vehicle motor l3 and I4 is connectedto the corresponding axle through a suitable drive shaft I5 and gearmechanism indicated generally at l6. Where the arrangement is such as torequire it, each drive shaft 15 a may be coupled to the correspondingvmotor armature shaft and gear mechanism by suitable universal jointcouplings I! as shown.

As indicated in Fig. 1 generally and more specifically in Figs. 2 and 3,the brake apparatus is suitably mounted and arranged in associatedrelation with the projecting end of each motor armature shaft so thatthe braking efiect on the vehicle wheels I 2 is necessarily effectedthrough the drive shaft l5 and gear mechanism l6.

Since the brake apparatus associated with each of the motors l3 and I4is substantially identical in structure, only that associated with themotor l3 will be described. s

As indicated in Figs. 2 and 3, the projecting end of the motor armatureshaft l8 has a brake drum l9 suitably fixed thereon, as by a key 2|, andarranged. in cooperative surrounding relation to the drum I9 is abrakedevice illustrated in the form of a circular brake band of suitablenature adapted to be contractedinto frictional clamping relation aroundthe peripheral outside surface of the drum l9 upon the supply of fluidunder pressure to a pair of suitable operating cylinders 23.

The operating cylinders 23 are mounted in fixed positions respectivelyon a plate member 24, hereinafter referred to as the torque plate, whichis journalled on the motor armature shaft has two branches leadingrespectively to each of the two operating cylinders 23, through whichpipe fluid under pressure may be supplied to the side of the piston 25opposite. the spring .21.

to cause movement thereof in a direction toeffect contraction of thebrakeba'n'd .22 about the brake drum. It will be apparentthat the twocylinders 23 are arranged so as to pull the corresponding ends of thebrake band 22 in opposite directions, thus causing the brake band toeffectively clasp the brake drum H in frictional braking relation. 7

I In order to hold the..brake band in a'substa'ntially fixed "position:with respect to the torque plate 24, a link 29 is pivotally connected atopposite ends' thereof to the torque plate 24 andthe brake band 22respectively.

Formed integrally with or attached to the torque plate 24 and arrangedperpendicular 'to the motor shaft |8 transversely of the wheel truck isan arm 3|, hereinafter referred tom the torque arm.

For the. purpose of restraining and controlling the" movement of thetorque arm 3| in response to the torque force exerted on the torqueplate 24upon contraction of the brake band 22 about the brake drum |9.whi1e' the vehicle is in motion, apair of cylinders '33 areprovided onopposite sides of and at-the outer-end ottbe torquearm 3|. .As shown inFig. 2; the cylin-, ders 33. may be suitably m'ounted as by brackets34secured to the frame of the vehicle motor.

Each cylinder 33 contains a movable ,abutment, illustrated as a piston35, which is nor: mally urged in the direction of the torque arm 3| by acoil spring 36, interposed between" the cylinder head and one face ofthe piston .35 so' that the piston isseated on an annular rib 31 formedon the head of the cylinder opposite the first mentioned head. The.piston 35 hasa'stem 38 which projects through the head of the cylinderand which is adapted to be engaged at its outer end by the torque arm3|.

Arranged on opposite sides of the torque arm 3| respectively, ininterposed relation between the torque arm and the adjacentcylinderhead, are a pair of ,coil springs 39 which serve, to center thetorque arm 3| in .anormal position providinga certain amount ofclearance between the torque armand the outer end of the pistonstems 38.The springs 39 are of sufficient strength-that, with the brake band 22in released position, movement ofthe torque arm 3| incidental to, road:shock during travel of the vehicle'along the. road is..not transmittedto the pistons 35 in the. cylinders 33, thus preventing oscillatorymovement of the pistons 35 in the cylinders 33 -under-normal conditionsand the consequent wear on the piston rings (not shown).

F'luidunder pressure kis -introduced into the cylinders 33 through "abranch rpipe 4| from a pipe 42, hereinafter called the control pipe,which extends longitudinally of a vehicle and,

pipe 42.

in the case of a train of cars, may extend throughout all cars of thetrain. Control pipe 42 is normally vented to atmospheric pressure and ischarged to a desired fluid pressure corresponding to a desired degree ofapplication of the wheel brakes by suitable means (not shown) under thedirect control of the operator or driver of the vehicle. The fluid underpressure introduced into each cylinder 33 exerts a force on the piston35 in the same direction as that of the .coil spring 36 and is therebyadapted to oppose -the rotational movement of the torque arm 3|in'..-accordance with the pressure established in the corresponding.cylinder 33 and control In order to; limit the maximum displacement ofthe torque arm 3| in either direction out of its normal'position, eachof the cylinders 33 may be provided with a suitable lug 48 arranged tobe engaged by the arm 3|.

. Associated with and adapted to be operated by movement of thetorquearm 3|is anslide valve mechanism 45, --the casing of which may besuitably attached to-on'e of the brackets 34 supporting one of thecylinders 33.

As shown in- Fig. 4 the casing of theslide valve mechanism is formed toprovide a slide valvechamber 46, and'aslide*valve 41 containedinchamber' 46, cooperates with a suitable slide valve seat 48. Slidevalve 41- has an operating rod 49 adjustably fixed thereto at one end,which rod extends through a suitable opening in the end coverbf'thejslide valve casingprovided with a packing 5| -and has its outer endpivoted, as on a pin 53,'to the torque arm.

The slide valve- 41 has two spaced ports 54 therein adapted when thetorque arm-3| is in its normal centered 'position, as shown, to registerwith correspondingspaced ports 55 inthe'slide valve seat 48 and openingout of a passage 28 to which the supply conduit 28, leading to the brakeoperating cylinders 23, is connected.

Formed in the slide valve 41 between the spaced ports 54 is a'cavity 56which is suflicientlylong to constantly register with an' exnected, asby a pipe 59 and the branchpipe 4| to-the control pipe 42.

A loaded check valve 6|, indicated as of the ball type, is provided forpreventingthe supply of the fluid underpressure-irom the slide valvechamber 46 to-the passage 28 through a connecting branch passage 62 andis arranged in such a manner as to permit the reverse flow of fluidtherepast from the passage 28 to the chamber 46 toenablethe release ofvfluid from the operating cylinders 23 independently of .the

position of the slidevalve, 41.

Operation Assuming that the vehicle or train is being driven under poweror coastingand the brakes are released, the control pipe 42 is atatmos-' pheric pressure and the torque arm 3| in its normal centeredposition. If it is' desired to effect application of the brakes-theoperator first cuts off the propulsion power, if the power is on, andthen causes the control pipe 42 to be charged to a fluid pressurecorresponding to the desired degree of application of the brakes.

Fluid under pressure. is accordingly supplied from thecontrol pipe 42 totheytwo cylinders. 33. thepistons 35 of which'are accordingly heldseated on the annular rib-31 associated therewith with a forcecorresponding to the degree of pressure established in the control pipe.At the same time, fluid under pressure is supplied through the branchpipes 4| and 59 to the slide valve chamber 46 of the slide valvemechanism 45 whence it flows to the operating cylinders 23 of the brakedevice associated with the armature shaft of the motor by way of theports 54 in the slide valve 41, ports 55 in the slide valve seat 48,passage 28 and pipe 28. It will be understood that the operation of thebrakes associated with the different motors |3 and I4 and axles l and IIis identical so that description of the operation for only one motor andaxle should suflice.

Upon the supply of fluid under pressure to the operating cylinders 23,the brake band 22 is correspondingly contracted in clasping relationaround the brake drum 19 to eifect an application of the brakes on thecorresponding vehicle wheels |2.

Assuming that the rotation of the vehicle wheels is such that thearmature shaft of the associated driving motor rotates in acounterclockwise direction as seen in Fig. 2, the torque force exertedon the torque plate 24 and torque arm 3| due to application of thebrakes tends to displace or shift the torque plate and arm in acounter-clockwise direction. The centering springs 39 offer only slightresistance to the movement of the torque arm 3| since their primarypurpose is merely to center the torque arm in its normal position.Accordingly, the torque arm 3| is promptly shifted into contact with theouter end of the piston stem 38 of the upper cylinder 33, whereuponfurther movement in a counter-clockwise direction is resisted by thefluid pressure force exerted on the piston 35 of the cylinder and theforce of the spring 36 acting on the same piston.

The operating cylinders 23 for contracting the brake band 22 about thebrake drum |9 are so designed that the torque force exerted at the endof the torque arm 3| against the piston stem 38 for a given controlpressure in the operating cylinders 23 is greater than the opposingforce exerted by the given fluid pressure in cylinder 33. Thus, when thepressure in the operating cylinders 23 of the brake device approachesthe pressure established in the control pipe 42, the torque forceexerted by the torque arm 3| overcomes the opposing force exerted on thepiston and consequently the torque arm moves in a counterclockwisedirection out of its normal position.

Due to the fact that the torque force on the torque arm continues toincrease as long as the ports 54 in the slide valve 41 register with theports in the slide valve seat 48, the torque arm 3| will continue tomove in a counter-clockwise direction until such time as the slide valve41 is shifted upwardly suificient to cut off or lap the ports 55. Whenthis occurs, the further supply of fluid under pressure to the brakeoperating cylinder 23 is cut off and further counter-clockwise movementof the torque arm 3| in a counte'r-clockwise direction ceases.

If the coefiicient of friction between the brake band 22 and the brakedrum l3 remains substantially constant for all speeds of rotation of thevehicle wheels, there will be substantially no further variation intorque force on the torque arm 3| and consequently the slide valve 41will remain in its lap position maintaining a substantially constantpressure in the brake cylinder 23. With a substantially constantcoefiicient of friction between" the brake band and the brake drum l9,and a constant operating pressure in the brake cylinder 23, the brakingeffort on the motor shaft H! and the connected vehicle wheel |2 willremain substantially constant throughout the application of the brakes.

If the coeflicient of friction between the brake band and the brake druml9 varies with the speed of rotation of the vehicle wheels, the torqueforce on the torque arm 3| will correspondingly vary and shift the armfurther in a counterclockwise direction or backwardly in a clockwisedirection toward its normal position depending upon whether thecoefficient of friction increases or decreases with reducing speed ofrotation of the vehicle Wheels.

If the arm 3| tends to be displaced further in a counterclockwisedirection out of its normal position, slide valve 41 will be shiftedupwardly,

out of its lap position, until arm 3| engages the stop lug 40 on theupper cylinder 33, in which position the upper port 55 in'the slidevalve seat will be connected by the cavity 56 in the slide valve 41. tothe exhaust port 51, thus locally venting fluid under pressure from thebrake cylinders 23 until such time as the torque force on the torque arm3|-is reduced sufliciently to permit the torque arm to be returnedtoward its normal position to restore the slide valve 47 to its lapposition.

If the torque on the torque arm 3| reduces due to a reduction of thecoeflicient of friction between the brake band 22 and the brake drums I9with reducing speed of rotation of the vehicle if wheels, the slidevalve 41 will move out of lap position downwardly until the ports 54 inthe slide valve partially register with the ports 55 in the slide valveseat 48, in which case fluid under pressure will be again supplied tothe brake cylinders 23 to further increase the pressure therein. Uponsuch increase of the pressure in the brake cylinders 23, the torque onthe torque arm 3| will correspondingly increase until the slide valve 47is shifted upwardly sufiiciently to lap the supply of fluid underpressure to the brake cylinders.

Thus, whether the coefiicient of frictionbetween the brake band 22 andbrake drum I9 is substantially constant, increases, or decreases withvariations in the rotative speed of; the vehicle wheels, the torquemechanism is automatically effective to regulate the pressure in thebrake operating cylinders to a value balancing the control pressure inthe cylinder 33. Accordingly, if the pressure established in the controlpipe 42 is high, then the torque control mechanism automaticallyregulates the braking force on the vehicle wheels to a correspondinglyhigh value and if the pressure established in the control pipe 42 isrelatively low then the torque control mechanism automatically regulatesthe braking force on the vehicle wheels to a correspondingly low value.1 p

It will be apparent that the control exercised by the torque responsivemechanism automatically compensates for differences in the coeflicientof friction between the brake band and brake drum of different brakeunits by regulating the fluid pressure in the corresponding brakeoperating cylinders to a value resulting in a substantially uniformtorque on the corresponding torque arm. Thus each brake unit isautomatically caused to contribute its proper share of braking effortfor a given degree of applicationof the brakes.

If the direction of rotation of the vehicle wheelsis such thatdue to-theapplication of the brakespthe torque forceexerted on the torque plate24and arm 3| displaces the, arm 3| in a clockwise direction,.then.ofcourse the lower cylinder 33 is effective to oppose'the displacementof the arm out of its normal position. In such case, the slide valve 41of the slide valve mechanism is shifted downwardly with; respect to itsnormal position and:the exhaust of fluid under pressure from the brakeoperating cylinders 23 is eflected'by" the cavity 56 in the slide valve4! connecting the'lowerport 55 in the slide valve seat 48 to the exhaustport 51 with the torque arm 3| engaging the stop lug 40 on the lowercylinder 33.

When the vehicle has been brought to. a stop due to the application ofthe brakes, the torque arm 3| remains displaced due to the frictionalforce exerted by the brake band 22 on the drum I9, thus holding theslide valve 41 in lap position holding thebrakes applied. If theoperator desires to release thebrakes prior to again starting thevehicle, he may effect the release of the brakes by merely reducing thepressure in the control pipe 42 to atmospheric pressure. Fluidunderpressureis thus released from the brake operating cylinders 23 byflow past the check valve 6| to the slide valve chamber 46 and thence byway of the control pipe 42 independently of the position of the slidevalve 41. When the pressure'in the cylinders 23 is reduced sufficiently,the frictionalforce holding torque arm 3| displaced is removed and thetorque arm is accordingly restored to its normal centered position,thereby restoring slide valve 41 to its normal position.

It should be'understood that if an operator de sires to'vary the degreeof a brake application from that initially selected, he may do so bycorrespondingly increasing or decreasing the pressure in control pipe42, in which case the torque apparatus automatically adjusts andregulates the pressure in the brake cylinders 23 to a pressurecorresponding to the control pipe pressure. a

In the application of my invention to a brake equipment for a train ofcars, it will be apparent that the control pipe 42 may extend throughoutall cars of the train so that variations of pressure in the control pipe42 will control thebrakes associated with all the brake units on all ofthe cars. It is not necessary however thatthe control pipe 42 extendthroughout all of the cars, it being essential only that the pressurein'the' control pipe 42 on each car of'a train be controlled uniformlyand in synchronism by any suitable means for accomplishing'such purpose.

It should be understoodmorecver'that while I have illustrated the torqueresponsive mechanism as associated with the armature shaft of propulsionmotors, it may be applied directly to a vehicle wheel or axle.

Embodiment shown in Figs. 5 to .9

cylinder .11 is.i-identical in construction and accordingly it is.deemed necessary to describe'the equipment for tonly 1 one wheel andaxle unit, whichawill be taken as that associated With-the motor 13.

The control equipment for each wheel andaxlc unit may comprise a controlvalve 12, similar to an enginemans straight-air valve, for controllingthe supply and release of fluid under pressure to and from the operatingcylinder 23, the operation of which is under the "joint control of thecontrol cylinder H and a torque responsive mechanism. 13 associatedwithgthe motor l3.

The control: cylinder H contains a movable abutment, illustrated as apiston 15, which has formed at one. side thereof a piston chamber"thatis constantly connected to the'control pipe 42a by a branch pipe'11. Interposed between the opposite side of piston 15. and 'thecorresponding end of the cylinder H is a calibrated coil spring 18 whichnormally urges the piston upwardly into seated relation on an annularrib seat 19 formed on the upper end cover or cylinder head 8!.

The piston 15 has a stem 82 which extends slidably througha suitableopening in the lower end of the cylinder and carries on the outer endthereof a cross-head member 83. The spring 18 is so calibratedthatdownward movement of the piston and the cross-head member 83 fromthe normal position thereof is substantially proportional to :thepressure established in thecontrol pipe 42a.

Thecontrol valve mechanism 12 may comprise a' casing having a so-calledpressure chamber formed therein, which is constantly connected to-thebrake operatingcylinders' 23 through a pipe or conduit 28a, and a pairof valves Hand 85, hereinafter referred to as the'supply valve and therelease valve respectively, foricontrolling the supply of fluid underpressure to the chamber 80 and the release of fluid under pressure fromthe chamber. As shown in Fig. 5, the supply valve 84 is contained in achamber 86 which is constantly connected through a branch pipe 81.-and asupply pipe 88 to a, reservoir 89 local to the vehicle and adapted to becharged with fluid under pressure in any suitable manner. The supplyvalve 84 is normally yieldingly urged into seated position on a suitablevalve seat to close a port 9| connecting the chamber 86 to the pressurechamber 80.

The release valve is contained in a cham ber 32,"which is constantlyopen to atmosphere through an exhaust-port 93, and is yieldingly urgedtoward a suitable valve seat'by a coil spring 94 .to close a port 95connecting the chamber 92 to the pressure chamber 80.

The supply and release valves 84 and 85 have operating stems 96 and 91,respectively, which extend'through the corresponding ports 9| and 95.into the pressure chamber 88 where they are adapted to be engagedbyopposite ends respectively of a lever -98that is fixed at a pointmidway between the ends'thereof to a rotary pin or shaft 99 journalledinthe casing.

One' end of'the shaft 99 extends through a suitable opening in the sidewall of the casing, which opening may be sealed against leakage of fluidunder pressure therethrough along shaft 93 from. chamber 80, and anoperating arm or handle IUI is .yieldingly attached to the end thereofoutside'the casing by a leaf spring I80 in a manner shown in Figs. 6 and'7 to cause rotation of the shaft 99. i'I'he-handle I BI is norcoasting,and that the operatordesires to effect application. ofthe brakes. ITo"do so, the opera tor first cuts ofi propulsion power; if the powerison,; and then causes the control pipe 42a to; be .charged. with fluid ata desired pressurexin' mally in a positionito cause'thes'upply valve84'to be seatedand the release valve85 to be unseated. When the handle isrotated out of its normal position, the release valve 85 and the supplyvalve 84 are successively closed and opened, the degree of opening ofthe supply valve depending upon the degree of displacement of theoperating handle IOI out of its normal position.

If handle I M is operated out of its normal po-- sition beyond themaximum opening of supply valve 96, leaf spring I yields'to permitmovement of the handle without movement of lever 98.

The torque responsive mechanism I3 comprises a torque plate 24a and atorque arm 3Ia,'corresponding respectively to the torque plate andtorque arm shown in Fig. 2, and a tubular casing I03 formed on orattached to the outer end of the torque arm 3I a. V

The tubular casing I03 is provided at one end thereof with an inwardlyextending flange I04 having a central opening I05, the opposite endbeing externally threaded to receive a screw collar I06 having a centralopening I0! therein.

A pair of flanged bushings I08 are provided which extend respectivelythrough the openings I05 and I0! and which are urged in oppositedirections by a coil spring I09 interposed therebetween within thetubular casing I03, the flange on the two bushings engaging the flangeI04 and the collar I06 respectively to limit the outward movement of thebushings.

The bushings I08 are provided with central bores I I I arranged invertical alignment for slidably receiving a tie rod II2 that ispivotally secured at its upper end to a fixed part of the vehicle truckframe, such as an arm IIO fixed to the frame of the motor I3. The tierod H2 is provided at its lower end with a suitable head II3, which isengaged by the outer end of the lower bushing I08, and is threaded onthe upper end thereof to receive a suitable nut H4 and lock nut II5adapted to be engaged by the outer end of the upper bushing I08.

Secured to each bushing I 08, as by a nut IIB screwed on the outerthreaded end of each bushing, is a transversely extending strap I I! ofrigid construction.

A Bowden wire having an outer flexible'armored sheath H8 and an innerflexible wire H9 is provided, the one end of the armored sheath I I8being suitably attached to the upper strap 7, as by welding in themanner indicated in Fig. 9, and the opposite end of the sheath beingsecured, as by welding, to the cross-head member 83 of the cylinder IIin the manner indicated in Fig. 8. The flexible wire H9 within thesheath II8 extends downwardly from the lower end of the sheath II8through a suitable guide lug I2I, integrally formed or attached to thetubular cas ing I03, and has the end thereof attached to the strap II!on the lower bushing I08. The opposite end of the flexible wire II9projects out of the end of the armored sheath secured to the cross-headmember 83 and has a yoke I23 attached thereto for receiving the outerend of the operating handle orarm IOI of the control valve mechanism 12,to effect rotary movement thereof in one direction away from its normalposition and in the opposite direction back toward its normal position.

Operation of embodiment shown inFz'g. 5

Let it be assumed that the vehicle is traveling along the road or track,either under power or the; manner indicated in. .connection with thefirst embodiment- .The. crossehead member 83- is correspondinglyshifted. downwardly an amount corresponding to the pressure establishedinthe control pipe 42a and the connected-piston chamber I6 ofcylinderII... Since the ends of the armored sheath H8 and of theflexible wire II9 opposite to those fixed to the cross-head member,

83 and the yoke. I23, respectively, are held in fixed'positions bytherespective straps I I! of the. torque mechanism I3, the downward.movement;

control valve mechanisms 12 in a corresponding:

direction.

Upon the shifting of I of thecontrolvalve. mechanism 12 inthe manfromthe pressure chamber 80 tothe exhaust port 93 and thereafter, as thedisplacement of the operating handle IOI out of its normal positioncontinues, the lsupply valve 84 is unseated and V fluid under pressureis accordingly supplied'from the reservoir 89sto the pressure chamber 80ofv each of the control'valve mechanisms I2 and thence to the respectivebrake cylinders 23v of thecorresponding wheel and axle units. If thedegree of downward movement of the -crosshead 83 exceeds that requiredto opensupply valve 84 a maximum degree, leaf spring I00 yields topermit the rotary movement ,ofhandle IOI relative to the rotary shaft90.

As the pressure. in the brake cylinders 23 increases, the torque exertedon eachatorque arm 3Ia is yieldingly resisted by the associated coilsprings I09 for either direction of displacement of the torque arm-outof its normal position. Assuming that the torque arm 3Ia associated withmotor I3 shiftsjin a counter-clockwise direction as seenv in Fig; 5, thetubular casing I03 slides upwardly relative to the upper bushing. I08,which is held against movement by engagement with the .'nut H4 1011'.the tie rod II2 that is in turn held in a. fixed position due to itsconnection to the motor frame, while the lower bushing-.l08 is shiftedupwardly, with the casing I03, on the tie rodflto .efiect acorresponding.

movement of thefiexible'wire' II9 longitudinally through'the'armoredsheath H8 to shift the yoke I23 away from the cross-head 83. Theoperating handle IOI of each control valve mechanism 12 is accordinglyshifted backwardly toward its nor mal po'sition'until the supply .Ivalve84 is reseated to cut. off the further supply of fluid under pressure tothe brake cylinders 23;

Just as in the caseof the first embodiment, ifv the coeificient offriction between the brake band 22 and the brake drum I9 remainssubstantially constant'throughout the brake application without anyvariation due to variations in the'rotative speed of the vehicle wheels,the control valve. mechanism I2 remains thereafter conditioned, asdescribed, in a lap position so that the brakes continue to be appliedatthe degree corresponding to the pressure established in'the control pipe42a. y

On the other hand, if the coefiicient of friction between the brake band22 and brake drum I9 the operating handle m increases or decreases.during theiapplicatio'n or the brakes, the-ftorquenarmxflmiwillxvbe'correspond'ingly shifted iurtheriaway from its-normal positionior backtoward its-fnorm'alzposition respectively jIni theievent of an 1increase in the ing' of the operatingzhandlerlllLot the control valvemechanism back toward the. normal. posi-: tion thereof, and the-releasevalve. 852 will ac-' cordingly be unseated to releasefluid under pres- Isure I from the brake. cylinders. 23. Such-"release of fluid.underjpressure will continue until thetorque on the torque arm 3 I aLc'orresponding'ly reduces to:- effect the. return of the 'releasevalveto seated position. I

In theevent that the tame-tor friction be; tweenrthe brake bandandlbrakeadrum decreases asthe speed of rotation. ofithevehicle'wheelsdecreases, the consequent reduction of the torque.

on the torque 'arm 3lawillefiect the unseating ofcth'e supply valve. .Insuchc'asefluid un-- der lpressure will be supplied to increase thepressure in the brake cylinders 23 until such time as the torque. onthetorque arm:.3la is again increased sufficiently to reseat the supply.valve It: will. thus .be apparent that: each torque mechanism .13functionsrautomatically .to eiTect operation of the controlyalvemechanism 12 cor-.

responding thereto to so adjust and regulate'the pressure in the brakecylinders 23. of the associated brake device as to maintain asubstantial- 1y constant braking. effort corresponding to the,pressure'iestablished' in the control pipe 42m If theoperator desirestovary thedegree of application of the brakes -from that initiallyselected, he may do so by correspondinglyincreasing or decreasing thepressure in the control pipe 42a. and the torque mechanism 13 willcorrespondingly respond to adiust and regulate the pressure in the brakecylinders '23- to a value corresponding to the pressure-established in.the pipeflan If thedirection of rotationrof the vehicle wheels suchthatthe torque arm. 3la asso.-.

ciated with motor 13 is displacedtin a clockwise direction as seen inFig.. 5,: the. lower bushing I08 of thetorque mechanism His heldstationary by the tie rod III while the upperbushing 1'08 is moveddownwardly withthe'tubular cas ing I03 toward the lower bushing,soi thatthe same movement of the-flexible wire H9 with respectv to the armoredsheath. H8. isiobtained as in the previous case, the ultimate resultbeing to effect operation of the controlvalve. 12" to vent fluid underpressure from the-brake operating cylinders 23 and. then. lap suchexhaust;

It will be seen that.,any .desired numberv oi control valves 12 may beoperated and controlled by the cross-head :member 83 of thecylinder 1|,only :two...va1ves being shown vfor purposes of illustration.

When the vehicle. comes1to. a. complete stop, the torque armMuismaintained in its displaced position by the frictional force.between thebrake band I22 and. drumQlS. against the force. ofspring-109.. Consequently the control valves [2 remain in lap lposition.and;the brakes. remain. applied until released; as presently; to rbedescribed. ;If' the operatorardesires to increase the degree ofapplication while the vehicle is st pped,

he ay. n rea s u e i con rp pipe 4.

to: se ti g f.suppl valve aiiQfth-e con-1;; 75; to beoperateduuporr anincreasing-displacement.

said valve means being normally --conditioned to.

trol: valves. '12 iniwhich case 1 the maximum pressure in reservoir89iis: establishedrzin thefbrake operating. cylinders 13:.because-the:torque mechanism I3 isnotthen'operative; to restore the supply valveitosseated position.

'When; the operator desires to releasexthe brakeslprior .to againstarting the vehicle, he merely causes: the" pressure in the control(pipe 42w to be reducedcto its :normal atmospheric pressure: ThespringxnoI-theicylinder 5' accordingly. restores-the piston-I5. andcross-head 83' to' their normal positions shown, in which the controlvalves 12' are operated to completely r.e leas'efluid under pressure.from the brake oper- I' ating cylinders '23 and thus completely releasethe brakes.

It will be appreciated that by providinga single spring, namely thevspring 109, in torque mechanism 13-for resistingthe movement of thetorque arm QIafineither directionpoimovement from its normal'position, auniform displacement of the torque arm for agiven torque force there-,on in either direction is obtained. It willalso be appreciated that byproviding a flexible conduit 28a for supplyingfluid under pressure tothe brake operating cylinders 23, the brake control equipment includingthe control valves 12 and the control cylinder H. may be mounted on thevehicle body or frameinstead -oi the vehicle wheel truck, the Bowdenwire including the flex-1 ible armored sheath H8 and the flexible wire II9 permitting a suitable connection between the cross-head 8.3 of thecylinder ll and the torque mechanism l3.-

Theprinciple of operation inherent in this invention whereby theapplication of the brakes is regulated, through: means responsive to thetorque exerted von. the brake means during an application of the:brakes, to any oneof a plurality of degrees; selected in accordancewith a variable control "fluid pressure is more broadly claimed thecopending application Serial No. 292,831 of Burton's. Aikman,flledAugust 31, 1939, and assigned to the'a'ssignee of this application.

While I havesho'wn only two. embodiments of my invention, 7 it will' beapparent that various omissions, additions or modiflcationsl may be madetherein without departing from the spirit of my invention. It isaccordingly not my intention to limit the scopeof my invention excep asrequired by the'scope .of the prior art.

Havingnow described my invention, what I claim as new and desireatosecure by-Letters Pat- ,-entis:

1. Vehicle brake, equipment comprising, in combination, fluid pressureoperated brake means for exerting a braking; force on a vehicle wheel,means movably responsive to the torque exerted on the brake meanszduringan application there-= of, a controlpi rgeablewith fluid at differentpressures corresponding-tea selected degree'of application; ofthe-brake; means, a ;mov-- able abutmentsubject-to the pressureestablished in said; control; pipe and arranged in a manner so that. thefluid pressure. force actingthereon opposes displacement of the saidtorque responsive means out ofa given normal; position there-.of,'-and-valvemeans havingan operating member connected to said! torqueresponsive means,

(establish communication through which fluid under pressure is'supplied'from said control pipe tothefluid pressure operated means and: adaptedof thetorque' responsive means out of its normal position tosuccessively cut ofi the supply of fluid under pressure to the fluidpressure operated brake means and release fluid under pressuretherefrom, whereby to control the operating pressure of the fluidpressure operated brake means so as to cause the brake means to exert asubstantially constant braking force corresponding to the degree ofpressure established in the said control pipe.

2. Vehicle brake equipment comprising, in combination, fluid pressureoperated brake means for exerting a braking force on a vehicle Wheel,means movably responsive to the torque exerted on the brake means duringan application thereof, a control pipe chargeable with fluid atdifferent pressures corresponding to a selected degree of application ofthe brake means, a movable abutment subject to the pressure establishedin said control pipe and arranged in a manner so that the fluid pressureforce acting thereon opposes displacement of the said torque responsivemeans out of a given normal position thereof, valve means having anoperating member connected to said torque responsive means, said valvemeans being normally conditioned to establish communication throughwhich fluid under pressure is supplied from said control pipe to thefluid pressure operated means and adapted to be operated upon anincreasing displacement of the torque responsive means out of its normalposition to successively cut off the supply of fluid under pressure tothe fluid pressure operated brake means and release fluid under pressuretherefrom, whereby to control the operating pressure of the fluidpressure operated brake means so as to cause the brake means to exert asubstantially constant braking force corresponding to the degree ofpressure established in the said control pipe, and check valve meansarranged to prevent the supply of fluid under pressure from said pipe tosaid fluid pressure operated brake means and adapted to permit therelease of fluid under pressure from the fluid pressure operated brakemeans upon a reduction of pressure in the control pipe independently ofsaid valve means.

3. Vehicle brake equipment comprising, in combination, fluid pressureoperated brake means for exerting a braking force on a vehicle Wheel,valve means having an operating element and adapted in a normal positionof the operating element to exhaust fluid under presure from the fluidpressure operated brake means and effective upon movement of theoperating element in one direction out of its normal position tosuccessively close the communication through which fluid is exhaustedfrom the fluid pressure operated brake means and open a communicationthrough which fluid under pressure is supplied to the fluid pressureoperated brake means, means for moving said operating element in saidone direction out of its normal position an amount corresponding to aselected degree of application of the brake means, and means responsiveto the torque exerted on the brake means for reversely moving the saidoperating element to cause said valve means to successively close thecommunication through which fluid under pressure is supplied to thefluid pressure brake means and open the exhaust communicatiomwhereby thesaid valve means controls the operating pressure of the fluid pressurebrake means so that the brake means exerts a braking force ofsubstanelement for said valve means effective in its normal position tocondition the valve means to exhaust fluid under pressure from the fluidpressure operated brake means and movable in one direction to cause thevalve means to be conditioned successively to lap the supply of fluidunder pressure in the brake cylinder and to supply fluid under pressureto the fluid pressure brake means and upon reverse movement toward itsnormal position to cause the valve means to successively lap the supplyof fluid under pressure to the fluid pressure operated brake means andto exhaust fluid under pressure therefrom, a control pipe chargeablewith fluid at diiferent pressures corresponding to a selected degree ofapplication of the brake means, fluid pressure responsive means subjectto the pressure in the said control pipe and movable difierent degreesout of a normal position according to the degree of pressure establishedin said pipe for effecting operation of the operating element of saidvalve means in said one direction a corresponding amount, and meansresponsive to the torque exerted on the fluid pressure operated brakemeans for, effecting reverse movement of said operating element of thevalve means while said fluid pressure responsive means remains in itsdisplaced position out of its normal position whereby to cause the valvemeans to regulate the operating pressure of the fluid pressure operatedbrake means to cause the brake means to effect a braking forcecorresponding substantially to the degree of pressure established insaid pipe.

5. Brake control equipment for a plurality of vehicle wheel and axleunits, comprising fluid pressure operated brake means for each of saidunits, an individual valve means for each of said units for controllingthe supply of fluid under pressure to and the release of fluid underpressure from the fluid pressure operated brake means correspondingthereto, each of said Valve means having an operating element adaptedwhen shifted in one direction to cause fluid under pressure to besupplied to the fluid pressure operated brake means and when shifted inthe opposite direction to successively cut off the supply of fluid underpressure to the fluid pressure brake means and release fluid underpressure therefrom, a control pipe chargeable with fluid at differentpressures corresponding to a selected degree of application of thebrakes, a single fluid pressure responsive means subject to the pressurein said pipe and shiftable out of a normal position thereof difierentdegrees according to th pressure established in said pipe tocorrespondingly effect operation of the operating elements of all ofsaid valve means in said one direction, and meansfor each of said unitsresponsive to the torque exerted on the corresponding brake means foreifecting reverse movement of the operating element of the correspondingvalve means whereby said valve means controls the operating pressure ofeach fluid pressure brake means so that the brake means exerts asubstantially constant braking force correspondingto the 'deg'reelofdisplacement ot the fluid pressure responsive means out of its normalposition.

6.-In combination; a rotary element, brake means for exerting aflbrakin'g force on said rotary element, means subject to thetorqueexerted on the brake means and shiftable in opposite directions outof anormalposition thereof for opposite "directions of rotation of saidrotary element, a Bowden wire having an outer flexible sheath and aninner flexible wire extending longitudinally through and movablelongitudinally with respect to saidsheath," means for moving said sheathand wire together in one direction out of a normal position an amountcorresponding to a selected degree of application of the brakes,andmeans adapted to cause movement only of the said flexible wire ofthesaid Bowden wire always in a direction opposite to said one direction.upon an increasing displacement of the torque responsive means out ofits normal position whether in one direction or the other out'of itsnormal position, and means controlled according to the movement of theflexible wire for controlling the brake means. '7. In combination, arotary "element, brake means for exerting a braking force on saidrotaryrelement, meanssubject to the torque exerted on said brake meansand shiftable in one direction or the other'out of a normal positiondepending upon the direction of rotation of the rotary element, a pairof members spaced apart, a coil spring interposed between said pair ofmembers and urging them apart, means for preventing movement of saidmembers except toward each other in a direction to compress the spring,said torque means being arranged to shift one of said members toward theother upon displacement of the torque means in one direction out of itsnormal position'and to shift the other of said members in the oppositedirection toward the other of said members to compress said spring upondisplacement of said torque means in the opposite direction out of itsnormal position, and means controlled according to the relativepositions of said two members for controlling said Mak means;

8. In combination, a rotary element, brake means for exerting a brakingforce on said rotary element, means subject to the torque exerted onsaid brake means .and shiftable in one direction or the other out of anormal position depending upon the direction of rotation of the rotaryelement, a pair of' members spaced apart, coil spring interposed betweensaid pair of members and urging them apart, means for preventingmovementof said members except toward each other in a direction tocompress the Spring,

said torque means being arranged to shift one of said' members towardthe other upon displacement of the torque means in one direction out ofits normal position and to shift the other of said members in'theopposite direction toward the other of said members to compress saidspring upon displacement of said torque means in the opposite directionout of its normal position, a Bowden wire having an outer flexiblesheath fixed at one end to and movable with one of said members and aninner flexible wire fixed .at'one end to and movable with the other ofsaid members whereby movement of said members toward each other isalways effective to cause movement of the flexible inner wirelongitudinally in one direction within the outer sheath, and meanscontrolled by movement of th inner flexible wire for controlling thesaid brake means.

9. In combination; a rotary element, brake means for exerting abrakingforce on said'rotary.element, means subject to the torque exertedon said brake means and shiftable in one direction or the otherout of anormal position depending upon the direction of rotation of the rotaryelement, a pair of members spaced apart, a coil spring interposedbetween said pair of members and urging them apart, means for preventingmovement of said members except towardeach otherlin adirection tocompress the spring, said torque means being arranged to shiftoneiofsaid members toward the other upon disto cause movement of theflexible inner wire longitudinally in one direction within the outersheath, movable means having a normal position and shiftabledifferentdegrees out of its normal position according to a selected degree ofapplication of the brakes, the end of the outer sheathwef said Bowdenwire opposite said one end being fixed to and movable with said movablemeans, and means controlled by movement of the flexible irmer wire,partly in accordance with the position of said movable means and partlyin accordance with the relative positions of the said two members, forcontrolling said brake means.

JOHNW. LOGAN, JR.

